A voter's nuanced opinion of a wide range of candidates isn't the subject of an election.

I believe that two party, pick A or B, voting gives people greater policy choice than other systems that accommodate niche tastes.

The latter come in a couple of flavors. One of those would be a proportional representation parliamentary system. You end up with a few fringe party seats that are rarely consequential and several of the larger factions keeping more or less stable shares of seats over time.

The range voting you describe would only serve to delete the strength of the plurality or majority the single winning candidate would show. This would not itself lend that office holder any greater legitimacy.

In the two party format, politically active people get fairly good input at the primary level, offering people the likelihood of a simple majority victory in the post-distillation process. That's frustrating for people who don't feel included in that two party choice, but if your candidate could make it through one of the party primaries, it is exceedingly unlikely he would prevail in any kind of general election.